(1) Field of the Invention
The present invention relates to a network definition modifying system, and more particularly, to a network definition modifying system which permits the definition of a network resource of a local computer system in a network to be modified independently of the operational states of other computer systems connected to the network.
(2) Description of the Related Art
In a network including a plurality of computer systems connected to one another, each system has a network definition which defines information about the network resource of its own system, as well as network definitions defining information about the network resources under the control of the other systems. When data communication is performed, the network resource of a local system is connected to that of a destination system in accordance with the network definitions.
FIG. 10 illustrates the configuration of a conventional network definition modifying system. In the center of the figure is shown a network 100a, which may be a leased line network or public switched network having a larger scale than a local area network. A plurality of computer systems, in the illustrated example, four computer systems 200a, 300a, 400a and 500a, are connected to the network 100a. These computer systems 200a, 300a, 400a and 500a each include a host computer to which several hundreds of user terminals, for example, are connected, though not shown in the figure.
The computer systems 200a, 300a, 400a and 500a have similar functions; therefore, the configuration of only one computer system is explained below taking the system 200a as a typical example. The computer system 200a comprises a console 201a which allows entry of data for the definition or modification of the network resource of its own system 200a and the network resources of the other systems; network definition processing means 202 for carrying out the definition or modification of network resources in accordance with the operation of the console 201a; a definition database 203 storing the definition information on network resources defined or modified by the network definition processing means 202; and communication means 206 which permits data communications between the network resource of its own system 200a and that of a target or destination system via the network 100a in accordance with the definition information on the network resource of its own system and that of the target system stored in the definition database 203.
In the definition database 203 are defined an address of the network resource of its own computer system 200a, a network address for entering the network, and addresses of the network resources of the other computer systems 300a, 400a and 500a. The communication means 206 is provided with a communications program and software including a telecommunications access method, and in the case of using such network resources for communications, the means 206 further defines an address of the network resource so that the network resource may be recognizable from the other systems.
When carrying out data communications through the communication means 206, the communications program specifies the name of the network resource of a destination system, and the access method searches the definition database for the addresses of the terminal of its own system and the terminal of the destination system, and then connects the systems to each other.
In the case where a configuration change has been made to the network resource of the local computer system 200a, the contents of the definitions in the definition database 203 are modified from the console 201a via the network definition processing means 202. For example, when a new terminal is connected to the computer system 200a, an address indicating the location of the terminal is additionally defined in the definition database 203.
Since the other systems cannot recognize the newly added terminal, the modified definition information is reflected in the definition databases of all related computer systems 300a, 400a and 500a. Namely, the definition information is exchanged with each of the computer systems 300a, 400a and 500a.
Thus, when the configuration of a system in the network is changed, it is necessary that the definition information be exchanged with each of the other systems, and exchanging the definition information between the systems permits automatic updating of the definition information in all systems. However, the time for changing the configuration is generally unforeseeable, therefore, the individual systems must always be in a state ready for communication with other systems. This inevitably involves a problem in that the systems between which the definition information is transferred must be operated according to an identical operation pattern, that is, the systems must be started and stopped at the same time.
Conventionally, two methods have been employed to transfer the definition information about network resource between systems. In the first method, the definition information is merely stored in a designated database. The second method utilizes a service that a duplicate of the definition information about the system is transferred when required, the service is included in a network directory system wherein vast resources are managed by means of a tree structure.
The first method requires a database for storing the definition information to be transmitted or received. Further, the definition of the network resource transferred to the database must first be converted to a format that the communication means can handle, and then stored in the definition database accessible from the communication means.
In the second method, the definition information must first be converted from the format which the database of the network directory system uses to a format that the communication means can handle, and then stored in the definition database accessible from the communication means. Furthermore, the network directory system must be in a state that the service for reading out a duplicate of the definition information is available.
In either method, even though the definition information on network resource is transferred successfully, it is not possible to determine whether the definition information has been properly converted to the format which the communication means can handle or whether the definition information has been stored in the target resource database. Further, in the case of using the network directory system, as in the second method, the required functions are not available unless the system is in operation.